This invention relates generally to shields for tractor power take-off shafts, commonly referred to as PTO shafts, and more particularly relates to a flip-up shield for a tractor PTO shaft.
In tractors provided with PTO shafts, the shaft projects a short distance from the tractor to receive a coupling on a drive shaft for an implement which is attached to the tractor. This coupling is usually part of a universal joint which allows movement of the drive shaft relative to the tractor PTO shaft. In such tractors it is customary to provide an inverted, U-shaped shield secured to the tractor and overlying the top and sides of the PTO shaft to prevent accidental engagement and possible entanglement with the PTO shaft.
Originally such shields were mounted on the tractor in a fixed position and were intended to be permanent. Often, however, the operator would remove the shield to obtain greater assessability to the PTO shaft for attaching or detaching the universal joint and then neglected to remount the shield. This results in a hazardous situation and circumvented the manufacturer's intent to have a safe vehicle. A solution to the operator removing the shield and failing to remount it is shown in U.S. Pat. No. 4,008,583 which issued on Feb. 22, 1977, to Lewis K. Davis, now Reissue Pat. No. Re. 30,152. This patent discloses an inverted U-shaped shield which is pivotally mounted on a tractor and normally assumes a PTO shaft protecting position in which the top wall of the shield extends generally horizontally over the PTO shaft and the sidewalls of the shield extend vertically alongside the PTO shaft. This shield can be pivoted upwardly and engaged in a position in which it leaves the PTO shaft exposed for easy coupling of an implement drive shaft. Once an implement drive shaft is attached, the shield is easily pivoted to its original shaft guarding position. This easy movement of the shield discouraged removal of the shield by the operator and has proven successful in use. Another advantage of this shield was that it could be pivoted to and retained in an intermediate position which permitted use of a large implement shaft with an oversized universal joint shield.
Many tractors are equipped with a trailer hitch which is secured to the tractor chassis above the PTO shaft and many of these hitches were secured to brackets for vertical adjustment to permit the trailer hitch to be positioned for the correct height for each particular trailer. In its lowest position, the adjustable trailer hitch could encroach upon the space occupied by the PTO shaft shield and require removal of the shield. In such a case, the advantages of the above-described flip-up shield would be lost, particularly if the operator failed to remount the shield after the trailer hitch had been raised.